package com.example.util;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;



public class DES {
    
  Key key;

  public DES(String str) {
    setKey(str);//生成密匙
  }

  public DES() {
    setKey("siyue_qi");
  }

  /**
   * 根据参数生成KEY
   */
  public void setKey(String strKey) {
      try {
        KeyGenerator _generator = KeyGenerator.getInstance("DES");
        _generator.init(new SecureRandom(strKey.getBytes()));
        this.key = _generator.generateKey();
        _generator = null;
      } catch (Exception e) {
        throw new RuntimeException(
            "Error initializing SqlMap class. Cause: " + e);
      }
  }

  /**
   * 加密String明文输入,String密文输出
   */
  public String getEncString(String strMing) {
      byte[] byteMi = null;
      byte[] byteMing = null;
      String strMi = "";
      
      try {
        byteMing = strMing.getBytes("UTF8");
        byteMi = this.getEncCode(byteMing);
        strMi = Base64.encode(byteMi);
      } catch (Exception e) {
        throw new RuntimeException(
            "Error initializing SqlMap class. Cause: " + e);
      } finally {
       
        byteMing = null;
        byteMi = null;
      }
      return strMi;
  }

  /**
   * 解密 以String密文输入,String明文输出
   * @param strMi
   * @return
   */
  public String getDesString(String strMi) {
    
      byte[] byteMing = null;
      byte[] byteMi = null;
      String strMing = "";
      try {
        byteMi = Base64.decode(strMi);
        byteMing = this.getDesCode(byteMi);
        strMing = new String(byteMing, "UTF8");
      } catch (Exception e) {
        throw new RuntimeException(
            "Error initializing SqlMap class. Cause: " + e);
      } finally {
       
        byteMing = null;
        byteMi = null;
      }
      return strMing;
  }

  /**
   * 加密以byte[]明文输入,byte[]密文输出
   * @param byteS
   * @return
   */
  private byte[] getEncCode(byte[] byteS) {
      byte[] byteFina = null;
      Cipher cipher;
      try {
        cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        byteFina = cipher.doFinal(byteS);
      } catch (Exception e) {
        throw new RuntimeException(
            "Error initializing SqlMap class. Cause: " + e);
      } finally {
        cipher = null;
      }
      return byteFina;
  }

  /**
   * 解密以byte[]密文输入,以byte[]明文输出
   * @param byteD
   * @return
   */
  private byte[] getDesCode(byte[] byteD) {
      Cipher cipher;
      byte[] byteFina = null;
      try {
        cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        byteFina = cipher.doFinal(byteD);
      } catch (Exception e) {
        throw new RuntimeException(
            "Error initializing SqlMap class. Cause: " + e);
      } finally {
        cipher = null;
      }
      return byteFina;
  }

  public static void main(String args[]) {
      DES des = new DES();
      // 设置密钥
      des.setKey("12345678");

      String str1 = "密文";
      //DES加密
      String str2 = des.getEncString(str1);
      String deStr = des.getDesString(str2);
      System.out.println("密文:" + str2);
      //DES解密
      System.out.println("明文:" + deStr);
  }
} 